The invention relates to using subordinate bus devices.
Computer systems typically have expansion buses, such as an Industry Standard Architecture (ISA) bus, an Extended Industry Standard Architecture (EISA) bus or a Peripheral Component Interconnect (PCI) bus. Coupled to these buses may be one or more bus devices that communicate with and are subordinate to a central processing unit (CPU) of the computer system.
One type of bus device subordinate to the CPU is an intelligent I/O (I.sub.2 O) processor. The I.sub.2 O processor typically furnishes a high level programming interface to I.sub.2 O subordinate bus devices (e.g., a Small Computer System Interface (SCSI) bus device) that are coupled to a separate bus (e.g., a SCSI bus) controlled by the I.sub.2 O processor. The CPU does not directly communicate with the I.sub.2 O subordinate bus devices but instead communicates with them through the I.sub.2 O processor. The CPU generates a high level logical request (e.g., a command to write data to a selected SCSI device) for one of the I.sub.2 O subordinate bus devices. The I.sub.2 O processor receives the logical request and generates the corresponding lower level physical commands for the I.sub.2 O subordinate bus devices necessary to carry out the high level logical request.